Which action should a financial institution take when it receives a grand-jury subpoena regarding a customer?

This action is inappropriate because it disregards the legal obligations imposed by the subpoena and could lead to non-compliance with the law. The institution must not act on verbal requests without proper legal advice, as maintaining accounts could interfere with an ongoing investigation.

Notifying the customer can potentially violate the terms of the subpoena and undermine the investigation. In many cases, subpoenas prohibit disclosure to the subject of the investigation to maintain the integrity of the proceedings, making this option legally risky.

Submitting original documents without legal counsel's review can compromise the institution's position and might violate confidentiality or privacy laws. It is essential to have legal oversight to ensure that any documents submitted are compliant and appropriately handled.